Tissue injury requires rapid and focal response of blood coagulation factors and cellular proliferation for repair. The cysteinyl-rich domains in many blood coagulation factors may play a central role in such a process. However, the functional roles of these domains are not well understood. The goals of this proposal target the role of these domains in the mechanism of blood coagulation. The proposal includes chemical synthesis and conformational study by NMR. Synthetic cysteinyl-rich domains of these blood coagulation factors and their variants will be prepared by the solid-phase methods. The solution conformation of thee synthetic molecules will be studied by 2D-NMR to correlate structure-activity studies. To determine the functional role of these cysteinyl-rich domains in the blood coagulation pathway, we propose to study the Ca2+-binding activity in Factors IX and X. In addition, synthetic analogs will be tested for their selective activity on mitogenicity and inhibitory activity against the binding of Factor IX to its receptor on the endothelial cell. Our long term goal is that the chemical, physical and biological studies of these cysteinyl-rich domains and their analogs will aid the understanding, on a molecular level, of the interaction and activation of various blood coagulation factors. This may ultimately lead to the design and synthesis of suitable analogs that function as inhibitors for the in vivo regulation of a specific coagulation factor.